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Sometimes, a sledge - hammer is the right tool ... :-)

An instrument designed for this type of troubleshooting is a milli-ohm meter, with a 4-wire test probe set and an audio generator that changes the pitch of the tone (from the internal speaker), as the very small changes in resistance are detected while probing around the board. The speaker tone allows the operator to focus attention on the test points, and not need to read the digital display constantly.

ToneOhm is a common term associated withh these type of testers, although it may be a tradename used by Polar.

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There have been many of the older, basic Polar models in the used instrument (and eBay) market.

The very basic model I bought (very inexpensivly on eBay) years ago wasn't a Polar, made in Britain instead, but I forget the manufacturer's name.

A basic instrument will have a couple of selectors for resolution and tone on/off.

Basic milliohm tester-type circuits can be found online.

-- Cheers, WB .............

Reply to
Wild_Bill
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You just like to argue. Don't you have something more constructive to do with your time?

--
Live Fast, Die Young and Leave a Pretty Corpse
Reply to
Meat Plow

Yuppers, I bought one on eBay shortly after this came up the last time, Fun part it is.

Jeff

Reply to
Jeffrey Angus

I forgot to mench, I haven't used the Bob Parker - AnaTek Blue ESR meter enough yet, to see how effective it is at finding hard shorted faults on boards. Since I'm not involved in repairs daily, I might not need to actually try the Blue model for quite some time.

Although, I should have something around here that I could purposely put a short on, and try the Blue ESR meter.

The speaker with varying tone on the toneohm-type tester is definitely a handy way to test.

-- Cheers, WB .............

Reply to
Wild_Bill

Yeah, I have a Toneohm 850A at work, but IMO they were too expensive for a single purpose such as that on my home bench. They're nice because you can use your ears to track and not have to keep looking up. The resolution is still only 100 micro ohms, though, same as the HP 3478A I mentioned.

Reply to
JW

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